they are two completely different things and a personal opinion that is not comparable, not to mention that we must also count the personal "taste".
personally I am attracted to mares, strictly faithful except if my partner approves (what happens rarely, if I try to cuddle some other mare she is often jealous, a lot, we consider that she is also the head of the group with which she lives), but when she is happened to be with some other mare, I must say that as a difference it passes a lot between those who are "virgin", those who had relations with the stallions, but did not give birth and those who gave birth. the first are let's say ... "curious" ... while those who gave birth (like mine) happen very often that they try to push you to have "more".
a very marked difference are the ponies (had only one, among other things it was my mare that brought her to me the first few times, with immense astonishment) the fact of being smaller is a completely different world and often use more strength when they wink that it's something stupid.
mine when he feels I am coming, arches his back and winks very strongly, it is a wonderful feeling, too bad that when he does so just finished (even in the meantime) he turns and comes to put his head on his chest for cuddles, that if he waited a little like the one I had (now star in the sky) it would have been much better, but each mare has a very different character.
the ponetta I was talking about earlier had to come two or three times before she decided to leave, but obviously if I was with mine she would only take it later or sometimes just with her hand
P.S. sorry for my english